Preheat the oven to 350 F. Spray a 9x13 baking pan with baking spray and set aside.
In a medium mixing bowl, whisk together the flour, baking soda and salt. In a large mixing bowl, whisk together the brown sugar, sugar, butter and vegetable oil. Next, add in the egg, egg yolks and vanilla and stir to combine. Add in the flour mixture and stir just until the flour is incorporated. Fold in the peanut butter m&m’s. Lastly, stir in the peanut butter.
2 ¾ cups flour, 1 ¼ tsp baking soda, ¾ tsp salt, 1 ¼ cups brown sugar, ½ cup sugar, ½ cup butter, ⅓ cup vegetable oil, 1 egg, 2 egg yolks, 1 tsp vanilla, 1 cup peanut butter m&m’s plus more for topping, ½ cup peanut butter
Smooth the bars batter into the prepared baking pan. Top with extra peanut butter m&m’s. Place into the oven to bake for 16-18 minutes or until the edges are golden brown. The center will feel almost unfinished. Do not worry about that as the residual heat will finish baking it. The center of the bars will fall after several minutes on the cooling rack - this is normal.
Once the bars have cooled, slice into 16 squares and serve.
Storage: Bars may be stored in an airtight container or baggie at room temp for up to 6 days. These can also be frozen for up to 3 months.